Transposition insulator



June 9, 1936. JOHNSON 2,043,754-

TRANSPOS IT ION INSULATOR Filed April 25, 1934 k I In vE/V 70/7. foe/w. F3 Jaw/501v.

'W YMJ/ Patented June 9, 1936 UNITED STATES PATENT ()FFICE 3 Claims.

My invention relates to insulators for use in radio frequency transmission lines and particularly to transposition insulators for such lines.

In many installationsof radio apparatus the radio frequency transmission lines associated therewith are transposed to nullify the effects of inductive and electrostatic interference from various external sources and to properly balance the lines. Such transpositions require the use of suitable insulator facilities for maintaining proper clearance between the respective conductors of the line in the portions of the line involved in transpositions. Various transposition insulators have been devised for this purpose but most of the insulators now available are, in one manner or another, more or less unsatisfactory. With some types of transposition insulators the plane of the pair of conductors transposed thereby is rotated through an appreciable angle at each transposition with the result that each individual transposition is incomplete and alternate insulators must be so applied that the plane of the conductors will be rotated alternately in opposite directions or else the pair of conductors will be arranged substantially in a double helix. Other types of transposition insulators are so constructed that the conductors must be threaded through apertures therein. In many types the conductors must be abruptly bent at right angles several times in passing through a transposition. Also, many transposition insulators are so constructed that the weight, wind resistance, electrostatic capacity, dielectric losses and electrical leakage are greater than desirable or necessary.

It is a general object of my invention to provide a transposition insulator for radio frequency transmission lines wherein the above enumerated objectionable features are eliminated.

An object of my invention is to provide such an insulator which may be quickly and easily mounted on a pair of wires without threading the wires through apertures and which will be supported and retained in position by the wires to which it is applied.

Another object is to provide such an insulator which will produce a complete transposition in a pair of wires to which it is applied and whereby the respective portions of said pair of wires extending from opposite sides thereof will lie in a common plane.

Yet another object is to provide such an insulator wherein each of the conductors of a pair to which it is applied need be bent at only two points and through substantially less than a right angle at each of these points.

Still another object is to provide such an insulator in which the wires to which it is applied need be deflected out of their normal plane only sufficiently to provide clearance between the wires at their point of crossing,

A further object is to provide such an insulator wherein substantially only tension and compression stresses are evolved in the respective portions thereof from the tension of the wires to which it is applied and which may be constructed from a relatively small amount of material.

A still further object is to provide such an insulator of simple and inexpensive construction wherein weight, wind resistance, electrostatic capacity, dielectric loss and electrical leakage are all minimized.

These and other objects and advantages of the invention will be more fully set forth in the following description made in connection with the accompanying drawing, in which like reference characters refer to similar parts throughout the several views, and in which:

Fig. 1 is a front view of my transposition insulator applied to and supported by a pair of conductors;

Fig. 2 is a top view of the same;

Fig. 3 is a side view;

Fig. 4 is a transverse sectional view taken along the line 44 of Fig. 2 as indicated by the arrows, and

Fig. 5 is a diagram of a radio frequency transmission line having transpositions therein.

Referring to the drawing, my transposition insulator for radio frequency transmission lines is preferably of one-piece integral construction and is formed of suitable electrical insulating material of a weatherproof nature such as glazed porcelain or the like.

In the following description, terms such as upper, lower, front, rear, right and left are to be applied to my transposition insulator as viewed in Fig. 1 wherein my insulator is shown attached to and supported by a vertically extending spaced pair of electrical conductors X and Y.

An upper horizontal member 6 and a lower horizontal member I, both of rectangular crosssection, are disposed in widely spaced parallel relation to each other with their longitudinal axes in a common vertical plane and their front and rear surfaces respectively in common vertical planes.

Immediately outwardly of each end of and formed integrally with each of the horizontal members 5 and l is an element 8 having the shape of a rectangular prism. The vertical dimension of each of the elements is the same as that of the members 6 and I so that its upper and lower surfaces respectively form continuations of the upper and lower surfaces of the horizontal members 6 and l. The horizontal dimension from front to rear is greater than that of the horizontal members 6 and I so that the elements 8 project respectively equal distances forwardly and rearwardly relative to the front and rear surfaces of the horizontal members 6 and 1.

End members 9 and it], each having a longitudinal axis disposed at a moderate acute angle with respect to the vertical, are integrally connected at their respective ends to vertically aligned pairs of the elements 8. The end members 9 and H3 each have a front to rear horizontal dimension approximately half as great as the front to rear horizontal dimension of the elements 8. The left-hand end member 9 is integrally attached at its upper end to the forward half of the bottom of the element 8 thereabove and at its lower end to the rear half of the upper side of the element 8 therebelow so as to slope downwardly and rearwardly at an acute angle as previously mentioned. The right-hand end member I is integrally attached at its upper end to the rear half of the bottom of the element 8 thereabove and at its lower end to the forward half of the upper side of the element 8 therebelow so as to slope downwardly and forwardly at an acute angle as previously mentioned. It is to be noted that the longitudinal axes of the end members 9 and ill are oppositely inclined relative to the vertical and at their respective midpoints intersect the vertical plane in which the longitudinal axes of the horizontal members 6 and 1 lie.

A Wire directing means or wire engaging element H of rectangular cross-section and having a front to rear horizontal dimension slightly less than half that of the elements 8 extends horizontally outwardly from the side of each of the elements 8 opposite to the side thereof to which one of the horizontal members 6 and I is joined. The upper left-hand and lower right-hand ones of the wire engaging elements I l are located with their rear sides flush with the rear sides of the elements 8 and the upper right-hand and lower left-hand ones of the elements II are located with their front sides flush with the front sides of the elements 8. It is to be noted that the inwardly facing sides of the respective wire engaging elements are substantially in the plane of the longitudinal axes of the horizontal members 6 and 7.

Each of the wire-engaging elements II is provided with a vertically extending wire engaging groove Ila in the side thereof opposite the side which is flush with a front or rear side of an element 8. The side of each of the grooves i la nearest the element 8 is disposed at the junction of the element 8 with the wire engaging element H. The bottom of the groove Ila comprises a wire engaging or directing surface and is spaced from the plane of the horizontal members 6 and l by approximately one-half the diameter of wires to be used with the insulator following element H.

A lug l2 extends outwardly from the outer side of the medial portion of each of the end members 9 and H) with its forward and rear sides flush with the corresponding sides of the end member from which it extends. The upper and lower sides of each of the lugs l2 are each disposed in a horizontal plane spaced vertically a short distance from the closest side of the wire engaging element H nearest thereto.

The sidewardly facing ends of the Wire-engaging elements I l and the lug l2 of each side of the insulator structure are all disposed in a common vertical plane.

The diagram of Fig. illustrates the transposition of a radio frequency transmission line between an antenna system A and radio apparatus R. The lead-in conductors X and Y comprising the transmission line are respectively connected to the antenna conductor A at opposite sides of a pair of insulators I which insulate twosections of the antenna conductor A from each other. The lead-in conductors X and Y are interchanged in position at each of the transpositions T as shown. At each of the transpositions T one of my transposition insulators is applied to the conductors X and Y in the manner illustrated in Fig. 1.

In applying my transposition insulator to the pair of lead-in conductors X and Y, the conductor X is disposed in the forwardly facing grooves Ha of the upper left-hand and lower right-hand wire engaging elements El and extends diagonally across the insulator at the rear side of the end members 9 and i0. Conductor Y is disposed in the rearwardly facing grooves Ha of the upper right-hand and lower left-hand wire engaging elements II and extends diagonally across the insulator at the front side of the end members 9 and Ill. The diagonal portions of the conductors X and Y are respectively deflected slightly rearwardly and forwardly from the plane in which the vertically disposed portions of the con ductors lie by the end members 9 and I0 against Y which the conductors bear. This deflection provides for clearance between the respective conductors X and Y at the point at which they cross and also functions to hold the conductors firmly in the grooves Ila of the wire-engaging elements II.

It is to be noted that the pair of conductors X and Y are, at respective sides of a transposition made with my insulator, in a common plane.

It then follows that the transposition is COIIl-i plete and that no twist is made in a pair of wires by the application of my insulator. It is also to be noted that my insulator will fit upon a pair of conductors in exactly the same manner regardless of which side of the insulator is facing i forward or which longitudinal edge thereof is uppermost.

It is apparent that a conductor, in passing through the insulator, need not be threaded through openings and is subjected toonly two bends and each of these bends is through only an angle of considerably less than ninety degrees. The insulator may obviously be applied to a previously installed pair of wires.

The tension of the wires X and Y will exert 6 large opening therethrough reduces the cost, weight and wind resistance thereof.

It will be noticed that at no point is a thin section of the insulator structure interposed between closely spaced portions of the respective conductors X and Y and hence that the electrostatic capacity between the conductors and the dielectric losses at a transposition are minimized. Also, the leakage paths between the respective conductors X and Y are both long and narrow and electrical leakage losses are therefore minimized.

Although my insulator has been described as applied to a vertically extending pair of wires, it is obvious that it may be applied just as readily to pairs of wires disposed in any attitude. Also, it is apparent that my insulator may be used with either bare or insulated wires and may be used in many classes of electrical circuits other than radio frequency transmission lines.

It is apparent that I have invented a novel, simple, inexpensive, effective and greatly improved transposition insulator for attachment to and support by a pair of wires whereby a complete transposition may be effected in the pair of wires with only two moderate bends in each wire and with the pair of wires entering and leaving the insulator in a common plane, wherein weight, wind resistance, electrical leakage, dielectric loss and electrostatic capacity between conductors are all minimized, wherein the stresses in the various portions of the insulator are limited to substantially pure compression and tension stresses, and which may be applied to a pair of wires without threading the wires through apertures in the insulator.

It will, of course, be understood that various changes may be made in the form, details, proportions and arrangement of the parts, without departing from the scope of my invention, which, generally stated, consists in a device capable of carrying out the objects above set forth and in the novel parts and combinations of parts disclosed and defined in the appended claims.

What is claimed is:

1. An insulator for transposing the respective wires of a parallel pair thereof comprising a generally rectangular body formed of insulating material and having a wire engaging means adjacent each corner thereof, wire engaging surfaces of said several wire engaging means facing and spaced approximately one-half the diameter of said wires from a common plane parallel to and intermediate of the faces of said body and alternate ones of said surfaces being arranged to face oppositely, said body having a depressed portion adjacent each of said means and toward the center of said insulator therefrom providing a wire guiding surface facing oppositely from the wire engaging surface associated therewith and away from said plane and slightly spaced from said plane whereby wires respectively engaging diagonally opposed pairs of said surfaces and passing diagonally of said body over corresponding pairs of said surfaces will be spaced apart a slight distance at their point of crossing.

2. An insulator for transposing the respective wires of a parallel pair thereof, said pair lying in a plane and having a longitudinal axis lying in said plane midway between and parallel to the respective wires of said pair, comprising, a

flat body having parallel front and rear faces disposed parallel to, at respectively opposite sides of and at respectively equal distances from said plane, wire engaging elements formed on said body and projecting outwardly relative to said axis respectively from opposite ends of the upper edge of said body and opposite ends of the lower edge of said body, one pair of diagonally oppositely located wire engaging elements being both offset rearwardly to have respective forward sides facing said plane and the remaining pair of said wire engaging elements being both offset forwardly to have respective rear sides facing said plane, said facing sides being spaced from said plane by approximately one-half the diameter of said wires, whereby one of said wires may extend across the front face of said body and the rear sides of said first pair of wire engaging elements and the other of said wires may extend across the rear face of said body and the front sides of said second pair of wire engaging elements to produce a transposition of the respective wires of said pair with portions of said pair extending in respectively opposite directions from said transposition disposed in said plane.

3. An insulator for transposing a pair of parallel wires through 180 degrees and maintaining said wires between respective ones of a series of said insulators in a single common plane comprising, a generally flat, generally rectangular open frame formed integrally of insulating ma-- terial and including side and end members, one of said end members extending diagonally from the front portion of an end of one of said side members to the rear portion of the corresponding end of the second of said side members and the other of said end members extending diagonally from the rear portion of the remaining end of said first mentioned side member to the front portion of the remaining end of said sec ond side member, and a wire engaging element projecting outwardly from each end of each of said side members, the ones of said elements associated respectively with the first mentioned end of the first mentioned side member and the last mentioned end of the last mentioned side member both being offset rearwardly relative to said frame and the remaining two of said elements being offset forwardly, each of said elements having a wire receiving groove in and extending across the side thereof opposite the direction of offset thereof and said offsets being such that the bottoms of said grooves face and are spaced from said common plane by approximately one-half the diameter of wires to which said insulator is to be applied, said end members having wire deflecting surfaces adjacent the respective ones of said grooves and facing oppositely therefrom, said surfaces being spaced a slight distance from said plane in the direction in which they face so as to deflect respective wires, in the portion of each thereof extending diagonally of said insulator between respective elements of one of the respective diagonally disposed pairs of said elements, slight distances in respectively opposite directions from said plane to maintain clearance between the diagonal portions of the respective wires.

EDGAR F. JOHNSON. 

